Method of delivering glass from furnaces.



G. E. HOWARD.

METHOD OF DELWERING GLASS FROM FURNACES.

APPLICATION HLED NOV. I5, i913- l atented Feb. 12, 1918.

wrrwzssas. W/ V all? M INVENTOR; I

, ouent working of the glass by ins, &c., after-it is delivered WEd A n union;

PLATE eLAss COMPANY, or PITTSBURGH,

rminsgnvanm.

ins-sesa- To all whom. it may concern:

Be it known that l, Gnonon E. Howann,

a citizen of the Uni-ted States, and resident ot Butler, in the count; of Butler and State of Pennsylvania, hare invented a new aru. nsetulImproi-emeut in li lethodsot Delivering Glass from. Furnaces; and I do hereby declare the following to be a. full, clear. and exact description thereof.

- My invention relates to" an in'iproved method of delivering molten glass from glass tank furnaces. and the object thereof is to deliver the glass from the furnace. in a comparatively large mass or body without the use of dipping: ladies and other means now employed; second. to deliver glass in large quantitie'squickly; to deliver the glass in predetermined quantities; and next to deliver the glass by the action of gravity. thereby avoiding many imperfections which are caused h ,'*"'forcihly delivering the glass by pressure and other methods now in use.

A: further object is to'deliver the glass in such manner that the entire surface of the glass may be under atmospheric pressure,- and in contact With'the furnace gases, where-- by unifhr'm temperature can be maintained throughout the mass o'f'the glass,. therehy avoid-ingthe uneven temperature in the molten glass which gives rise to defects caused by differences ofternperature between the surface of the glass and the interiorof the mass, or differences or temperature between different portions of the'molte n glass.

T his invention A does not relate to the methods '0f5m'elting glass nor to the subserolling, drawfrom thetank. The delivered glass can be discharged into a .pot and afterward-poured on a casting table or pouredinto drawing pots and cylinders of glass drawn in the usual manner, or it can he delivered directly onto a table for rolling into sheets. Again it can be delivered through a spent with one end higher than the tank level 'a'nd the other end connected to the melting tank at a lower level I p means a'fiow of glass can he 7 and by this maintained in the spout which will be usein] for gathering for hollow ware.

When glassis worked it is in a semiiluid or. viscous state, and resembles soft dough in consistency... When t is being melted it he eniesvery thm and hot and impurities Specification of Letters Tatent.

so that it disappears altogether. suits in great PENNSYLVANIA, A CORPORATION OF METHOD 0E DELIVERING GLASS FROM FURNACES.

Patented Feb. 12,1918.

I Application filed Kovcmber 15, 1913. SerialNo, 301,270.

readily escape. For working into sheets and for melting it is In handling large masses of glassentirely difiereutfmethods must be employed from those n'iei hods sometimes practn-ahlc for gathering orladling small quantities Cspecially is thist'r'uc in the art of plate glass making, where the finished product must be free. from impurities, and, especially free from that detect known as ream.

team is a wavy effect present in glass and caused by the disturbance of its grain or homogeneous character. its effect is to so disturb the refractory property of the glass as to distort obiccls seen through it first allowed to c0ol,.'then it is worked i'n'this viscous past-y cond tion.

even though the glass is perfectly solid and ground and polished.

Ream is frequently caused by agitation oi the body of the glass and invariably occurs -\-'-'hcnever the glass finished in tank or pot) is poured in a small stream -from the, tank or pot and united again into a mass. Such a mass when rolled or Worked is full of rearny streaks showing where the stream of glass has united mechanically with themass, but with greatdamage to its retracting properties by reason of the. fact that the skin which invariably forms on an exposed surface of thernoiten glass is never 'thor oughly assimilated with the rest ofthe mass This re damage to the retracting In making large lenses for optical work the avoidance cl. ream is so important'that the glass is not Worked when hot, but the pot is allowed to properties of the glass.

cool and the glass to anneal by cooling oti glass, thus left in its undisturbed state.

In plate glass the retracting property is also highly important. though not-so delicate a property as with lenses. Plate glass can onlybe produced commercially by work ing the glass in large masses in order to rerent-ream. I

The present day inethod of glass is to dump the entire pot in a mass on the rolling table, care being taken to roll out the mass with the least amount of disturbapeer The glass has to be worked ra'piclly and the pot is tipped suddenly so theta: discharges the glass in making plate contents of the fractory. clay can be immersed into the body of glass without serious production of ream,

provided these blocks are not entirely withdrawn from the glass, which mightresult in a drip on the main body or mass.

This immersion can be effected rapidly Without serious detriment. This is taken advantage of in my delivery method, and Whatever resemblance the various elements employed may have to certain existing means, it is believed that the method of using them is entirely novel.

In on rrying out my method of operation for the production of glasswithout ream, care must be taken to have the plungers smooth and without pockets which might trap air and-cause bubbles to be taken into the mass of glass. The glass adheres to the plungers, but as they are withdrawn this glass is not severed from the main body, but remains integral with it, and slowly flows back intb the main body by gravity.

I secure the operation of my improved method as follows:-

The tank containing the glass is divided into two compartments, a melting compare ment proper, and a refining and discharging ,compartment or chamber, separated by a partition Wall near the bottom of which is a communichting passage to permit the glass to flow from the melting chamber to the discharge chamber. The plungers are suspended preferably in the discharge cham her. and normally at such-a height that only their lower ends are immersed in the glass.

The glass slowlypasses through the eomvmunicating aperture to cause the level in the discharge chamber to rise to the level in, the melting chamber.

Next, comparatively rapid lowering of the plnngers eauses'tho glass to quickly rise in the discharge chamber. The delivery spout. from the discharge chamber, whic can be made as wide a desired, furnishes means for a free gravity flow on to a tableor into a pot in a comparatively short period of time. Should. the .levol'in the discharge chamber be higher than that in the melt. ing chamber, some glass will flew back into the melting chamber, but it is the intent of this method to have the delivery spout delivery spout is not pertinent to this method. It isprcfcrahly as high or higher than the level of the glass in the melting tank, so that during periods between opcrations, or when operations are suspended, as on Sundays or holidays, when manufacturing operations cease, there will be no flow of glass from the delivery spout.

However, this level of the delivery spout can be placed considerably lower than the level of the glass in the melting tank, and when the level in the discharge chamber reaches this delivery spout level, the plungers can be rapidly immersed and a rapid delivery effected. Upon the withdrawa'l of the plungers the level in the discharge chamber will fall below the level of the bottom of the delivery spout, and remain below it until suliicient glass has flowed through. the communicating opening between the melting chamber and the dis charge chamber to raise the level in the spout, whereupon, the operation of glass delivery is repeated. With the delivery-spout so arranged at a low level, it is obvious that the tank must be continuously operated, which would ordinarily be objectionable. Such arrangement is here mentioned only as a possible one, and does not result in a material difference in the method of operation, which is the object of this invention.

It is possible also to so proportion the levels of the delivery spout tothe zlass level in the melting chamber that the level in the discharge chamber, aftcr'th'e plungers are immersed, will be no higher than the level in the melting chamber, and, consequently, no back flow is caused inthe commumcating opening between the melting chamber and the delivery chamber.

Neither of these last two arrangements are preferable, but mention is madeof them' to show that this method does not depend upon any arbitrary arrangement of levels, and to show that any such modifications come within the scope of this invention;

The main principle employed in this method consists in the ditlerentidl timecelement, that is, delivery takes place at a much The shorter the time taken for delivery relative to the time for feeding from the melting.

to the discharge chamber, the greater will be. the flow ofglass through the delivery I d/Vhde it. '15 not essential to the principle of this method, itniay be stated that norntes of time.

tanks, a similar condition to. that produced when glass is poured 'over the. edge of a pot. orthrong'h a large opening by its natural gravity and a tendency to a, reamy condit ion is eliminated; "this character :tic of molten glass so well understood especially in the plate glass business, has lun'etoforc prevented. tlie. use of any mechanismnot using the natural surface flow.

The principle employed in my invention causes the raising of the level ol the glass in the delivery reservoir and alloxvsit to flow over the-edge of the discharge opening from the surface much in the manner of glass pouring over the edge ot a pot. This allows the particles of molten glass to asstime. their natnral position in flowing. The delivery reservoir is open to thc interior of the furnace allowing the furnace gases to play freely on the surface of the molten glass and thus maintain a uniform temperatu'r The lcrel of glass is regulated by displacement as hereinbefore described. Theamount delivered will be proportional to the amount. of this displacement and the corresponding rise in level' In order that the invention may be thorough'l y' understood I have illustrated herein one form of apparatusby which the method may be carried out; -In the drawings Figure 1 is a vertical longitudinal section of a ftirnace showing a mechanism for delivering the molten glass, embodying the invention; Fig. 2 is aview similar tol ig. 1 showing the 'plungers in discharging position; and Fig. 3 is a horizontal section on the line 38 Fig. 1 of the apparatus.

In the embodiment of the invention here- Jin selected for illustration, 1 represents a glass furnace having melting compartments 2 and a delivery or dischar' e chamber 3 separated from the melting compartment by a partition Wall at having at the base thereof a passage 5 for communicating-between the melting and delivery chambers,- glass flows through the passage 5 from the melting compartment into the delivery chamber thus bringing the. level in the latter up to that in the former. The surface of the glass in both chambers in will be noted is 0 en to the interior of'the furnace and thus t cheat of glass when in the mass.

molten glasssubstantially up to-the outlet spout l), the pltlngers which .are normally held in position sothal only the lower ends thereof are innnersed in the molten glass, may be lowered together or in succession. or mlepart of them may be operated. The lowering (of the plungcrs in the glass and deliver) chamber will ohriously raise the level of the glass in said chamber hy'displacement oi its contents. .The glass will then flow out through thospout (3 by gravity. The rise oi level of the glass in the dclivel'y chamber will he proportionate to the displacement effected by the plunger. By reason ol the. passage hetn'eenthc melting and delivery chambers a certain amount of glass will necessarily flow back through the opening into the melting chamber as the level in the delivery chamber is raised. But as this opening 5 is small and the time of discharge short, it is obvious that only a small portion of glass will flow back, the greatest part will flow through the dis charge spout 6,'as this may be made as large and as wide as desired. The speed at which the plu'ngcrs are lowered will determine largely the speed at which the level of the glass will rise. This, however,v willnot ma tcrially affect the speed at which the glass discharged through the spout 6 as this depends entirely on the action of gravity and will be. determined both by the amount of rise in the level and also the condition of viscosity of the molten glass. Since molten glass is a perfect. fluid, and not compressible, the level in the delivery chamber Will rise exactly proportionate to the speed of displacement of the plunger.

the particles of the glass assume their'nat ural position by gravity Whichis an essen tial condition, and experience has shown that -this does not detrimentally afiect the i t is obvious that the'o'peration does not depend on the particular form of the plungers or the material from which they are.

made, provided they are of such structure as to displace appreciable quantities of glass and thus raise the level of the glass in the delivery chamber. T hisinvention therefore constitutes a modified form of the iriven tion disclosed and claimed in my co-pending application, Serial No. 78%,896, filed August 15, 1913.

Several advantages flow from the method of discharge accomplished by this apparatus, but principally the following, to. wit; The glass can be delivered in large bulk as the width of the delivery spout may he as great as desired. The chan e in level or displacement of the glass in elivery chamber may be regulated according to the quan tity of glass required. Furthermore, a wide discharge openingand a considerable rise in level 'Wlll cause the quick delivery of a large quantity of glass. Furthermore, the amount of glass discharged Will be proportionate with the amount of displacement and thus a. predetermined quantity of glass may be delivered. Again, the discharge or delivery is effected by a rise of level and therefore results'entirely from the action of gravity. Finally, the discharge reservoir being 0 en to the interior of the furnace, the sur ace of tlie glass Will receive the heat of the furnace gases freely and will be maintained in good uniform condition.

retreat The method obviously may be car-fried out by other forms of apparatus than that herein showmbut said apparatus will serve to illus trate the principle upon which the invention rests.

What I claim is:

1. The method of delivering; molten glass from a tank furnace ha ing a delivery chamberl constantly comm unicatiinga-w it h the melting chamber, which consists in feeding the glass into a displacement chamber through a relatively small opening, raising its level in delivery chamber by displacement, and thereafter dischargingsame through an opening of relatively large area.

The method of delivering molten g iss from tank furnace having delivery chamber constantly comnmnicatrg with the melting chamber, which consists in feeding glass into a displacement cliainlm' during a con'iparatively long interval of time, ralsing the level of glass in delivery chamher by displacement, and thereby discliarg ing glass from displacement chamber in a. comparatively short time.

In testimony whereof, I the said. Gnome E. I-Iowann have hereunto set my hand- GEOI GE HOWARD. /Vitnesses ROBERT C. TOTIEN, JOHN F. l/V1LL. 

